Introduction

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The goal of this corpus of music and the analysis thereof is to find out what kinds of distinctions Spotify makes between different kinds of alternative ‘emo’ music. The styles that I am interested in include math rock, post rock and Midwest (emo). To those uninitiated in the cult, I will give a brief introduction, as well as give an example of what I consider a typical track for these styles.

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Math rock

Math rock is characterized by harmonically rich chords, often involving major sixth, all kinds of seven and nine, eleven and thirteen chords. Rhythmically, the music rarely follows a 4/4 structure, often changing time signatures throughout songs. The style of playing that is most notable in the often very present and highly technical electric guitars can be described as ‘angular’ with big intervals and high contrasts in syncopation, as well as accenting off-beats frequently.

A typical track could be: Bubble Dream by Chon

Post rock

Post rock is harmonically similar to math rock, hence why the two are often grouped together. Post rock, however, conveys a much different emotion, which I would personally describe as “positive solitude”, like being very alone and being okay with that. The style is much calmer and less ‘angular’ than math rock, and thrives on winding repetitions of somewhat meditative leitmotifs, often preceded by sonically big crescendos.

Your hand in mine by Explosions in the Sky is distinctly post rock.

Midwest emo

This style is a bit harder to describe, as it features much of the same characteristics of the previous two styles, but in varying degrees. Midwest can be very peaceful or feature metal-esque screaming, depending on the song and artist. A common trait, one that is shared in most emo music, is yelling vocals. The previous two styles are typically instrumental, whereas this style usually offers emotional or downright depressing lyrics for the listener to enjoy or wallow in. It still features the same harmonic ideas, and really employs a minor mode.

Never meant by American Football is the most famous and ubiquitous example.

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Exploring the distinctions between math rock, post rock, and Midwest emo using the characteristics provided by the Spotify API presents an intriguing challenge. There is much debate among fans about the boundaries and overlap of these genres, hence why such an analysis could be meaningful. An example of an outlier could be Polyphia, which is traditionally a math rock/metal band that turned more to an electronic and hip hop influenced instrumental boy band. Where would they land on the spectrum? Through the use of the toolset provided by Spotify, new insights in this subset of emo-genres can be gained.

Dancing to the Beatles compared to my corpus

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When looking at any corpus of music, an interesting point of debate can be the measure of how easy this music is to dance to, or perhaps, how inclined one naturally feels to move to the rhythm upon hearing a tune. To this end, Spotify provides an API endpoint for previously discussed features, one of which being ‘danceability’. To both gain a better understanding of my chosen corpus of music, as well as to gain insight into this parameter, two figures have been displayed.

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Corpus energy metric spread

Beatles (best of) energy metrics spread

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We can observe that my selected styles of music would serve marginally less well in a dancing hall as compared to the Beatles on average, according to Spotify that is. This also reveals a bit of the bias of this danceability feature, as some of the tracks in my corpus would do fine in, for instance, a more meditative style of dancing. The Beatles also score a bit lower than I would expect, since they have released numerous radio and dance venue hits. This, however, seems to be the nature of this feature. Martin Garrix for example, a renowned Dance DJ/producer, averages around 0.6 ‘danceability’ when looking at his five most popular songs.

Does Polyphia make Light work, or rather LIT?

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Chromagram of the Polyphia track “Light”

Chromagram of the Polyphia track “LIT”

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These are two versions of the same song, both released by the band Polyphia. The original version, ‘Light’, features a lot more of the band’s original sound, with technical intertwining guitar parts and prog-rock-esque rhythms. In the rerelease, called ‘LIT’, the band opts for a strongly electronic sound. While the electric guitars are still clearly distinguishable, it is obvious that a lot of studio work has gone into this version of the track. It also features typical elements of dance music, such as opening and closing of filters and compressors, a strong bass drum and background effects to fill up the sound. This last part is interesting, as the chromagram appears a bit more smeared or less distinct in the electronic version. Perhaps these smears over the spectrum are these very effects, as they are often not clearly pitched. Other than that, there appear not to be many major differences.

A math rock classic’s self similarity

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A recurrent theme in post rock is repetition itself, as previously mentioned. A nice example thereof is the track “Frozen Twilight” by God is an Astronaut. As this track is over six minutes long and features several sections, one would expect to be able to recognize these when compared to itself at a different time by using a Self-Similarity Matrix (SSM).

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Frozen Twilight SSM for Chroma and Timbre

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Interestingly, the timbre of the track remains much the same throughout the song.This reveals that perceived intensity is minimally reflected in the ‘timbre’ feature, as there are very noticeable differences in energy throughout the song.

Camp Adventure tempograms

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For the sake of the assignment and my amusement, we compare the tempograms of two different versions of the same track: Camp Adventure by Delta Sleep. The first version is from the album ‘Management’ and is from 2013, while the second version comes from the album ‘Twin Galaxies’ (2015).

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Twin Galaxies (2015)

Management (2013)

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The more popular version from 2015 appears a bit more temporally consistent. This can be explained by the distinct ‘live’ sound of the Management version, which Spotify attributes the value of 37% against the later version’s 30%. The acousticness is also much higher for the Management version at 92% against 15%.

Both these versions are considered by Spotify to belong to the following genres: math rock, math pop, British math rock, Brighton indie, while Wikipedia attributes them both to Indie rock and math rock. While looking at these genres one may conclude that geographical information is also used to classify genres, Delta Sleep originated in Canterbury, Canada.

Rhythmic Complexity Analyses

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Rhythm and tempo

As previously mentioned, rhythmic complexity is a defining characteristic for math rock in particular. To this end, this page aims to grant insight in the rhythmic intricacy that many of these tracks feature. To create a measure of ‘complexity’, the Root Mean Square (RMS) of both the tempo and the time signature features of the Spotify API are compared. Since both of these are not to be entirely taken at face value, combining and averaging them may prove to be a better metric. I considered including the confidence of these values in this figure as well, but that would likely not yield a better result, as it’s hard to say whether a low confidence score should increase or decrease perceived complexity (for example, a spoken bridge section may result in hugely complex structure, according to Spotify).

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RMS Comparison

Spy Dolphin - Delta Sleep

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The RMS figure

This figure shows two possible measures for perceived rhythmic complexity. Noteworthy here is that the spotify algorithm for time signature detection is quite limited, in that it only returns any signature from 3/4 to 7/4, and also isn’t very reliable for complex tracks. In the Spotify API, besides actual tempo changes, perceived tempo changes may also mean a new time signature or off-beat rhythm is established, hence why it is included in this figure.

A good example

A particular example is Spy Dolphin - Delta Sleep. Besides being a very well-crafted song (unbiased), it is also interesting in the rhythm department. Most of the song can be counted along in 4/4, though some interesting syncopation may be interpreted as a different time signature. The end of the song is in 7/4 time, which Spotify picks up on. It is one of the more ‘complex’ tracks when strictly looking at tempo RMS.

---
title: "Index"
author: "Marijn Oude Groeneger"
date: "2024-02-21"
output: 
  flexdashboard::flex_dashboard:
    storyboard: true
    orientation: rows
    social: menu
    source: embed
---

```{r setup_main, include=FALSE}

library(tidyverse)
library(spotifyr)
library(ggplot2)
library(plotly)
library(compmus)
```


Introduction
================================================
```{r Introduction, child = 'introduction.Rmd'}
```

Dancing to the Beatles compared to my corpus
================================================

```{r Dance, child = 'corpus_beatles_dance.Rmd'}
```

Does Polyphia make Light work, or rather LIT?
================================================
```{r Polyphia Chromagrams, child = 'polyphia_chromagrams.Rmd'}
```

A math rock classic's self similarity
================================================
```{r Frozen Twilight SSM, child = 'frozen_twilight.Rmd'}
```

Camp Adventure tempograms
=================================================
```{r Camp Adventure, child = 'camp_adventure.Rmd'}
```

Rhythmic Complexity Analyses
=================================================
```{r Rhythmic Complexity Analyses, child = 'tempo.Rmd'}
```